REM & EM to PX Calculator

Convert rem and em to pixels (and px to rem) using your own root font size—ideal for design systems and fluid typography.

Root font size

px (default in browsers is often 16px)

rem → px

rem

Result: 16.0000px

px → rem

Result: 1.000000 rem

em → px

em is relative to the parent element's font size. Set the parent font size in px below.

Parent font size (px)

Result: 16.0000px

Quick reference

rem is always relative to the root element (html). em is relative to the current element's font size (or the parent's, depending on property)—for font-size, it compounds.

Need display density? Try the PPI calculator or breakpoint checker.

Default root size

Browsers often default to 16px on the root. If your site changes html { font-size: ... }, adjust the root field so rem math matches production.